Severe. These medicines may interact and cause very harmful effects and are usually not taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
Both medicines can cause liver problems and problems with your blood.
What might happen:
You may not be able to take enough trimetrexate safely to cure your Pneumocystis carinii pneumonia (PCP).
What you should do about this interaction:
Contact your healthcare professionals (e.g. doctor or pharmacist) as soon as possible about taking these medicines together. Your doctor will need to monitor you closely while you are taking them. Your doctor may want to change your antiviral medicines while you are taking trimetrexate.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.Reference:1.Neutrexin (trimetrexate glucuronate for injection) US prescribing information. MedImmune Oncology, Inc. January, 2005..